Enter Pregnancy Details
Example Data Table
| Method | Reference Date | Cycle Length | Estimated Due Date | Example Countdown Snapshot |
|---|---|---|---|---|
| Last menstrual period | January 10, 2026 | 28 days | October 17, 2026 | Gestational age and countdown update daily. |
| Known conception date | February 1, 2026 | Not required | October 25, 2026 | Useful for closely tracked ovulation cycles. |
| IVF 3-day transfer | March 5, 2026 | Not required | November 23, 2026 | Dates adjust to embryo age automatically. |
| Known due date | December 4, 2026 | Not required | December 4, 2026 | Works well after a confirmed scan. |
Formula Used
This calculator uses standard obstetric dating rules and IVF-specific adjustments to estimate the due date, gestational age, remaining time, and pregnancy milestones.
- LMP method: Due date = LMP + 280 days + (cycle length − 28 days).
- Conception method: Due date = conception date + 266 days.
- IVF 3-day transfer: Due date = transfer date + 263 days.
- IVF 5-day transfer: Due date = transfer date + 261 days.
- Known due date: Pregnancy start equivalent = due date − 280 days.
- Countdown: Remaining days = due date − today.
- Gestational age: Today − pregnancy start equivalent.
- Progress percentage: (elapsed pregnancy days ÷ total pregnancy days) × 100.
Real pregnancies can differ from estimated schedules. Ultrasound dating and clinician guidance should take priority when available.
How to Use This Calculator
- Select the calculation method that matches your pregnancy records.
- Enter the matching date, such as your LMP, conception, transfer, or known due date.
- Adjust cycle length only when using the LMP method.
- Press Calculate Countdown to show the result above the form.
- Review the due date, gestational age, trimester, milestones, and graph.
- Use the CSV or PDF buttons to save or share the estimate.
Frequently Asked Questions
1) How accurate is a due date countdown?
It is an estimate based on standard pregnancy dating rules. Actual delivery dates vary. Clinical ultrasound dating and your care team should guide final timing decisions.
2) Which method should I choose?
Use LMP for typical cycle-based dating, conception when ovulation timing is known, IVF transfer for assisted treatment, or known due date when a clinician already confirmed it.
3) Why does cycle length matter with LMP?
Longer or shorter cycles can shift ovulation timing. Adjusting cycle length helps align the estimate more closely with your probable conception window.
4) Does the calculator show overdue time?
Yes. If today is after the estimated due date, the result switches from remaining time to overdue days and updates the chart accordingly.
5) Why is IVF dating different?
IVF timing uses embryo age and transfer day, which gives a more precise dating basis than cycle assumptions alone. That is why 3-day and 5-day transfers use different offsets.
6) Can I use this after an ultrasound?
Yes, especially with the known due date option. Enter the confirmed due date and the calculator will rebuild the countdown and milestone timeline around it.
7) What does pregnancy progress percentage mean?
It shows how much of the estimated pregnancy timeline has elapsed, based on the selected dating method. It is a planning indicator, not a health measurement.
8) Should this replace medical advice?
No. This tool is helpful for planning and tracking, but pregnancy care decisions should always be based on professional medical evaluation and personalized guidance.